Terrible internet service provider and customer support that doesn't do anything.

1. We signed a contract with a provider NOS because agent promised to give us a voucher for the purchase of a TV set of 140 euros. As a result, only 100 euros were sent and the support service does not want to do anything. At first they said that they could not do anything. Then they promised to transfer the case to a higher department and call back, but they never called.

2. After signing the contract, we contacted the support service and each agent told us different information about the contract and the voucher.

3. The voucher came only after 2 weeks, so we cannot to cancel the contract. It turns out that we were deceived, because when signing the contract we were promised completely different conditions.

4. As a result, when we were told that they would not help, we bought a TV from the provider NOS with a voucher that was given to us and the TV does not work well. Either a black screen appears, the screen becomes darker, then lighter.

NOS are liars who do not want to do anything in order to somehow correct the mistake of employees. I want to solve the problem and give me an answer.