Being threatened by bulb but have been paying monthly?

Can anyone advise? We were charged a late payment fee in September despite paying, and this payment showing on my bulb account. I rang and someone sorted this out for me but then we’ve been charged another one in November despite making monthly payments in both October and November??? Today, I’ve received an email saying a debt collector will be in touch over my £32 debt (despite the fact that approx half of this is the wrongful late payment fee).

It’s BULB’s system failure that is causing this error and yet it’s me being threatened. Can someone please make it make sense.

Afraid the blub accountancy system is broken beyond rectification by us mere mortals.
The best I can advise is the OFFICIAL complaints form|(at the bottoom of this page)and if it is not resolved within eight(8) weeks escalate it to the energy ombudsman