Just Eat complaint: KFC food ordered via Just Eat with some food missing

I ordered via Just Eat (10 piece bargain bucket deal – Total: £21.73 – includes card fee and delivery cost). Delivery arrived with 4 chicken pieces missing cold. Just Eat refused to give refund via payment card or via discount via email. They kept insisting they had sent discount for missing chicken pieces as credit in my Just Eat account. This was not the case despite my protests online via website chat for over 3 hours with several different offshore staff members; my matter was not successfully dealt with. Left me feeling deflated and conned. Phoned the actual restaurant who were unhelpful advised to contact Just Eat to resolve matter. I did all that I was instructed to by Just Eat staff but it appears they have very poor customer service, very bad log in issues and website. Difficulties logging on despite changing passwords more than once. Feel I have wasted my time and money on this purchase with KFC and nobody has been willing to help with this issue, what should have been an enjoyable meal indoors. Any assistance would be appreciated