Not happy customer

Paslyn joyce consultant from onair she called me around March offering me explorer decoder she said i will only pay R320 i will no longer pay R400 i asked her many times about the R320 she yes i will only pay R320, on April the debited the R320 i didn't pay the R400 as she said i will not be paying it until the contract finishes they cut off my package i called Dstv to find out why they said i didn't pay my package they said i must paid R550, R400 for the package R50 for connection and R100 for catch up i paid R870 on April unprepared paslyn didn't tell me all bout this money and is too much for me i want to cancel the contract they said i wont be able to cancel it because the decoders where installed, one of the decoder its not working their installation guy called me to install the second decoder which is working fine i took the 1st decoder which was not working to Dstv shop in Johannesburg they said they wont fix it because it doesn't have package, on the 16 of May 2020i send an email to onair about my query they said they will investigate until today they didn't reply about my query they just calling me about payment. I want to cancel the contract