Product stock not reducing!!

Hi all,
https://www.driphacks.com
system report:

### WordPress Environment ###

Home URL: https://driphacks.com
Site URL: https://driphacks.com
WC Version: 2.6.13
Log Directory Writable: ?
WP Version: 4.7.2
WP Multisite: –
WP Memory Limit: 512 MB
WP Debug Mode: –
WP Cron: ?
Language: en_GB

### Server Environment ###

Server Info: Apache
PHP Version: 5.6.27
PHP Post Max Size: 100 MB
PHP Time Limit: 300
PHP Max Input Vars: 4000
cURL Version: 7.45.0
OpenSSL/1.0.1e

SUHOSIN Installed: –
MySQL Version: 5.6.32
Max Upload Size: 100 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 2.6.13
: 
woocommerce_sessions: ?
woocommerce_api_keys: ?
woocommerce_attribute_taxonomies: ?
woocommerce_downloadable_product_permissions: ?
woocommerce_order_items: ?
woocommerce_order_itemmeta: ?
woocommerce_tax_rates: ?
woocommerce_tax_rate_locations: ?
woocommerce_shipping_zones: ?
woocommerce_shipping_zone_locations: ?
woocommerce_shipping_zone_methods: ?
woocommerce_payment_tokens: ?
woocommerce_payment_tokenmeta: ?
MaxMind GeoIP Database: ?

### Active Plugins (23) ###

Advanced CSS Editor: by Hardeep Asrani – 3.0
Akismet: by Automattic – 3.2
Contact Form 7: by Takayuki Miyoshi – 4.6.1
Custom My Account for Woocommerce: by phoeniixx – 1.2.3
Instagram Feed: by Smash Balloon – 1.4.8
Instock Email Alert for Woocommerce: by Laszlo Kruchio – 1.1.2
Jetpack by WordPress.com: by Automattic – 4.5
Min and Max Quantity for WooCommerce: by BeRocket – 1.0.2
Postman SMTP: by Jason Hendriks – 1.7.2
Simple Custom CSS: by John Regan
Danny Van Kooten – 3.3

Compress JPEG & PNG images: by TinyPNG – 2.1.0
Unite Gallery Lite: by Valiano – 1.7.40
Visual Form Builder: by Matthew Muro – 2.9.2
Advanced Flat Rate Shipping Method WooCommerce: by Multidots – 2.3
WooCommerce Print Invoice & Delivery Note: by Triggvy Gunderson – 4.1.5
WooCommerce DYMO Print: by WP Fortune – 2.5.5
WooCommerce SagePay Form and SagePay Direct Gateway: by Add On Enterprises (Andrew Benbow) – 3.3.3 – 3.3.6 is available
WooCommerce Product Add-on: by Najeeb Ahmad – 2.5
WooCommerce: by WooThemes – 2.6.13
WooSidebars: by WooThemes – 1.4.3
WooCommerce Helper: by WooCommerce – 1.7.2
WP Simple Paypal Shopping cart: by Tips and Tricks HQ
Ruhul Amin
mra13 – 4.2.9

WP-Mail-SMTP: by Callum Macdonald – 0.10.1

### Settings ###

Force SSL: –
Currency: GBP (￡)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2

### API ###

API Enabled: ?

### WC Pages ###

Shop Base: ? Page ID is set
but the page does not exist

Basket: #54 - /your-cart/
Checkout: #74 - /checkout/
My Account: #75 - /my-account/

### Taxonomies ###

Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)

### Theme ###

Name: Relia
Version: 1.0.7
Author URL: https://smartcatdesign.net
Child Theme: ? – If you're modifying WooCommerce on a parent theme you didn't build personally
then we recommend using a child theme. See: How to create a child theme

WooCommerce Support: ?

### Templates ###

Overrides: relia/woocommerce/archive-product.php
relia/woocommerce/single-product.php

We have a huge problem at the moment and I cannot see where the problem is coming from. None of our products are managing stock properly, stock should decrease when orders are placed but it doesn’t happen. Stock levels remain consistent and no longer reflect what we have in.

This is a HUGE problem for us as we sell a lot of items and cannot afford to sell something we don’t have, this leads to shipping delays, refunds and a bad customer experience.

“Manage Stock” and “do not allow back-orders” are both selected but they dot seem to be working. Does anyone know what could be wrong here? I am in desperate need of a fix for this!!

Thank you.