Incorrect Treatment Duration Time

I paid for a 120 minute treatment. I received a 90 minute treatment today . I have informed the Reception of the treatment time upon arrival and still she continued to say it's only a 90 minute treatment. I have sent a mail now . Awaiting there response . I doubt I will receive any . I received all the promised treatments . I am happy with that part . But not the duration time . I have paid for a 120 minute treatment.