Very poor service from mtn

My mother has a Microsoft phone which was sent in February to have sorted out they have not resolved this and she has to use a much cheaper phone to conduct her business. They have not delivered on their promises and she has been a client for well over 10years I think it's time for a change coz no one needs to wait so long for any repairs this is ridiculous and unprofessional. I think my mother and I and my family should just change our Network coz we have experienced to many issues