Threatening my safety and disgusting service

I have been trying to sort a query out with Citiq since Nov 2018. We had moved in to a new house in October 2018 and at the end of that month we received a water bill which was paid but the next month's water bill, according to Citiq was 18000kl more than the previous month. This is impossible as I had stopped my garden service from coming and started using less water, i even had a council worker to have a look and see if maybe something had been wrong and even he informed me that the water usage was way too high for the size of the house i stayed in, however the water bills just kept getting bigger and bigger, thus i stopped paying and lodged a query with Citiq which resulted in me receiving a phone call from them stating me to "Pay up or else" . Through the months the house was put on the market without me even being notified of such, i had to see the house on the internet to see it was for sale. During this time i have been trying to resolve this query but it is impossible to contact Citiq. the phone lines don't work and nobody responds to emails. Due to me not paying the water because of an ongoing query, we were threatened by debt collectors constantly saying they are going to disconnect my water (which is *******, we all have a right to water). The evening before vacating the premises i received an sms from Citiq to say that there are debt collectors waiting for me outside my house, this was at 20h00 at night. This is clearly threatening my safety. i have now vacated this house as it was sold. Citiq refuses to respond to any email or telephonic contact regarding the return of the deposit. i tried to discuss this in the past but was told they WILL NOT communicate with me until i move out. I have moved out but still no contact. My emails are still ignored. The service from Citiq Properties is absolutely disgusting.