Sorry to hear about this happening to you. Similar happened to me a couple of years ago. I lost my landline phone number of 20+ years, and had to have it replaced with another number for some reason that didn't sound very likely. After multiple calls and hours on the phone over several days, there was absolute refusal to reinstate the old service, despite being promised initially if I paid the full amount for reconnection (which I did) that I would receive a credit / refund for connection charge, and account would be reinstated along with my existing phone number.
My suggestion would be to put in claim with Ombudsman as soon as practical (within the boundaries of Ombudsmans limits of oversight) if you aren't being provided with the service that you have contracted for / or are requesting as per services offered.
You haven't requested the cancellation of your service, so you should be provided with the reason why/who initialted the cancellation, or the reinstatement of your service, possibly with compensation / credit for days without telephony (from memory there is a mandatory payment required by statue).
One thing to watch for with a prepaid service is that should your payment method fail (ie new credit card) providers have been known not to make positive contact with the account holder and the situation arises where a customer account is closed, leaving the customer with no internet/phone and no apparent option but to arrange for and pay the fees for reconnection. This is not acceptable where the customer has not knowingly missed their payment, and likely a situation the Ombudsman would award in the customers favour, shoudl they make a complaint. It might be worthwhile checking your account payment status. If this has happened you should be told this is the reason for the "request to close the account" which is actually an internal request to the appropriate actioner to but from experience this may not be disclosed to you until multiple calls later, wasting a lot of time and frustration.
Best of luck...
Thanks for raising this to our attention and we apologise for the inconvenience.
We understand that you've been in touch with our Accounts team and advised that a new account will be processed.
Further updates will be given by your case manager as soon as it becomes available.
We're truly sorry for the inconvenience caused. We can clearly understand your aim to obtain an immediate resolution on this complaint you have raised.
I have since chased the relevant departments involved in your case to provide pertinent updates tomorrow.