Multiple calls and my query is still not resolved

It is now close to a month from my first call to resolve a case of misselling on a contract upgrade where incorrect promises were made. Since then multiple calls and holding for 40 minutes on one occasion and I still have not managed to get this issue resolved. Apparently they did decide to cancel the upgrade as requested, but then I had to phone to hear if this was done. Only to find out that it was apparently done on the wrong number. Since then I still have not heard a thing again. The last agent's English and voice was so unclear I had to ask three times after each sentence what she actually said. Horrible customer experience. I'm actually thinking of cancelling all my contracts.