VFS “Scheduled Visa Reservation Exists” error?

Basically what the title states — I’ve already completed and paid for my visa application. However, I’m unable to book my biometric appointment. My British partner’s mother has graciously offered to pay for all of the services I need regarding said biometric appointment. The first time we tried paying using one of her cards, we got an error stating “there was trouble processing your payment” or something to that effect, and we were told to wait 150 minutes before trying again.

We waited and were then able to try booking again. Sadly, we can’t even get to the screen where you enter your payment details now because we get an error at the top stating “Scheduled Visa Reservation Exists” and we are unable to progress any further beyond that screen.

I’ve seen others in this subreddit who’ve dealt with this error say they just canceled their application and submitted a new one and were successful getting a biometric that way. However, with the salary requirements changing on 11th April and the amount of time it would take that money to be refunded to my fiancé (who kindly paid for my visa app), cancelling my current app and submitting a new one is just not feasible for us.

I’ve already reached out to the VFS customer care Twitter and emailed them through their Feedback form on their “Contact Us” page. They’ve given me a generic response through DMs on Twitter requesting more details from me, but of course, they’ve been shamefully slow getting back with me. Any advice on what more I can do? I am desperately seeking help on this issue and anything anyone can provide in terms of useful information is incredibly appreciated. Thanks in advance.