Handed over for no reason. Service appalling!

Absolutely shocking. Billing system has been a mess since you migrated to the new system over 2 years ago. For over 2 years we never receive any automated statements/invoices and why is it me, as the client, that constantly has to take time out of my day to phone and chase up invoices. I have been handed over to debt collecters even though everything is paid in full and there is a debit order in place. Furthermore, I paid in full an invoice that was under query and to date no investigation has been done. No communication from you at all. No requests for payment, no demands, nothing. Just handed over for absolutely nothing. How dare you!! You had better hope this has not affected my credit rating or my legal team will be in contact with you!