Contact them if you need help
Like others, I used the top-up facility once (my partner paid for it) and did not want a subscription. But a month later another payment was taken out of my partner’s bank account. I went to the Onetopup website and used their contact system to tell them about this. To their credit, they got back to me within 24 hours, investigated the situation, and sorted a refund. All I had to do was provide a screenshot of my partner’s bank statement, showing the unwanted subscription payment. So although I was concerned after reading their reviews on here, they acted promptly with personal emails (instead of generic ‘Your enquiry is being dealt with’ messages).
Reply from On Top Up