MISSING PREPAID

The new prepaid metering leaves much to wish for - someone is *****ing money from me/probably us. I have prepaid a certain amount and was never credited on my meter, after several mails to them they have made absolutely no attempt to resolve the matter, just simply no reply at all. At one stage i managed to get a call through, the excuse was that they are behind or something and will not cut me off. An ad hock letter from them some time later and probably not related to my query at all (think it was a general letter to all) stated that i/we are using the incorrect reference numbers, which is in my case not true at all because prior to that and after that i have used the same fixed reference number and both payments reflected - the one in between is missing and they are not fixing the problem - so according to me it is money disappearing/****** - or what else ???.