ProUpgrade left my site basically disabled

I installed this plugin when I built the site a year ago. It worked well and was easy to use.

However, now that some of the features are only active with a paid subscription, my site is having all kinds of problems, including pages that only link to blank pages.

I built my website for a small business which uses it for their customers to make online payments and accept new customers with an online form. They haven’t been able to accept any payments for the last week because of this. They don’t want to pay extra for a feature that was originally free and I don’t blame them. They are a small business who wanted a website made and couldn’t afford the thousands of dollars required to pay some big company to make one. I’m no expert, admittedly, but this plugin has caused me a mountain of headaches and now I have to basically redo their website since half the pages no longer exist and the page editor is the source of the problem.

I understand that everyone is out here to make a living but part of the reason I used this plugin was because of all the features offered in the free version. Now the 3 or 4 features I used most are no longer available without payment so my website a mess and my customers are very frustrated.