Incorrect upgrade information provided

In July I requested my contract to be cancelled due as the 24month period expired. I wanted to move to FNB for the R399 package with unlimited call option. Oupa at Vodacom canecllation department convinced me not to move and offered a red premium plus package for R699 pm. 10G data, unlimited SMS, and Unlimited calls. I was charged R1800 and my next bill will be R2000. 12 different people and still they can not resolve my query