I purchased a 6 pack...

I purchased a 6 pack of Longlife milk from my local store and the milk was fresh when you drink it cold but the minute you start warming it up it changes its form and taste I took back the remainder to spar for refund and unfortunately they could not refund me for the one they i have already used, they escalated the matter to Farmgate which has never tried till today to get back to me and explain