Continual harassment without dealing with the matter

some 5 years ago I installed a Vox Telecom system at my office. From day 1 I was charged for items that I did not require and did not receive. Every time I queried this I was assured that the necessary credits would be passed. This never happened. With a move of office happening on 30 August 2019, I again, unsuccessfully, tried to get this matter resolved and eventually at the end of July gave notice of termination of their services for the end of August. Needless to say I was charged for September and I reversed the debit orders for both August and September. The overcharges were still substantially more than my August charge. I initially got some threatening emails and phone calls from Vox and on numerous occassions forwarded them copies of correspondence from 2014. This was not acted on and I was handed to Debt-in. They seem worse than VOX, phoning and emailing numerous times a day. I have forwarded my VOX correspondence at least 7 times and when I bring this up with them I am told that I am speaking to a call center and someone else must have spoken to me.

I have invited them to issue summons, which would be met with a counter claim, but they will rather pester with unacceptable phone calls. Unfortunately as quickly as you block their calls as spam, they change number.