as others have said , the rear exhaust is supported by heavy duty
"rubber bands"..designed to let the exhaust move a little,
so the problem will be they either broke a band putting the new exhaust in - which they should have replaced..!!,
or they didn't align the new parts of the exhaust correctly( there is SOME flexibility), which a trained person will allow for and CENTRE the exhaust properly,
either way ..NO it isn't right.., and NO and they will NOT have to charge you more to fix it,