URGENT Prestashop web development / bug fixes

Indigoextra is an international SEO and web design company.

We've had ongoing issues with the https://addons.prestashop.com/en/combinaisons-customization/22091-custom-product-designer-product-customization.html module on 2 different sites, plus some payment issues and am looking for an experienced PrestaShop developer to fix them.

The 2 urgent problems are:
- Currently if someone orders multiple products in the same order it says that some of them are out of stock.
- There are issues accepting payment by credit card from certain countries (this is less urgent, as the client also accepts PayPal, so there's a workaround).

We're using an old version of the Custom Product Designer module that's been customised over time by different developers. I'm not a developer myself, rather I'm an SEO expert, and unfortunately aren't aware of what elements of code have been changed.

The ideal solution would be to:
- Disable stock control completely (all products are in stock all the time, however when we disabled it, it caused problems).
- Upgrade the Custom Product Designer module from v1.4.2 to v3.1.2
- Thoroughly test the website to ensure all features still work and various combinations of products can be ordered.
- Fix any bugs that appear.

That said, I'm open to other solutions.

We're looking to work with an experienced and competent Prestashop developer or agency who communicate well. We also look after several websites in Drupal and WordPress websites, so experience in these would be a bonus, but is not essential.

We rarely use PPH, however on Upwork have spent over $100k and have a 4.98/5 rating from 136 reviews. We're therefore a serious buyer with the potential to offer long-term work on future projects.

I look forward to hearing from you.