Can't resubscribe on monthly subscription?

I had an annual subscription to ProAI which lapsed last week. I want to resubscribe on a monthly basis but the app will only let me purchase an annual subscription and following the advice here: Monthly subscriptions still available? If not, what are the cancellation policies? doesn’t work because it just defaults back to annual every time.

Have emailed support about this but no response. I’m trying to give you guys money here and there seems to be no interest!

Any help greatly appreciated, thank you