Not working good on mobile

HI. I’ve created my woocommerce website, and inside most of products i put a select field. (4-8-12 months). So i have the product with the montly price. Like 150€/month. In this product I put the select field that is required and a person has to choose from those 3 options before buy (in this case is 4, 8, 12 months). When a person choose 4 months, the price is gonna be x4, so 600€ total. The problem is that when I click on Add to cart button from outside of the page, he adds to cart the item with the single month (150€). How can i solve this? Instead of add to cart from archieve pages, he should redirect me on the product page where the people can choose for how long they want this service. The rest is working fine on desktop.
On the mobile, even if i go on the single product page, i see ONLY Add to cart button and it does the same thing. Add to cart the product for the price of a single month.
After i add to cart the item, and go back on the same product page, i can see the select field and the slider…Anyone can help me? thanks