Up to no good as usual mtn

Today I went into store for clarification... Lady who helped me with signing up for modem contact, denied saying it would work at other premises,when I would definitely not have taken the router if wouldn't,as have uncapped at home... So I asked to cancel contract,I was told to call a number to cancel...this evening I called in to cancel,just to be told I need to go into store to cancel... PATHETIC SERVICE...and should inform clients of changes, 4 months of wasted fees ..