Incorrect seats allocated and no answer at customer service

I booked tickets with BA Comair and pre-booked and pay extra for specific seats. At the point of check-in I was allocated different (middle) seats. When I tried to change the seats to select new seats the system kicked me out. Going back onto the check-in program we were checked in already with the incorrect seats. You cannot get hold of their customer service centre - this is shocking - absolutely no customer service. I will never book through BA Comair again.