I don't know about the take over, but this last year I had with E2Save/CPW they only took a bit of prompting on one of the cashbacks. The last one.
I used a sales call they gave me to my advantage when they called me up to say they could sort me out a better contract, approx. transcript below:
O: "Hi, this is E2Save, your phone contract has just run out, we can get you a better one cheaper."
A: "That's brilliant, Where's my cashback?"
O: "That's handled by a different department, we can give you a really good deal for your loyalty."
A: "I'm sure you can, matey, but first you go away and talk to that different department, then when I get my £96 you owe me, we'll talk like friends, until then, you're just someone who owes me £96 and I've told friends to F--- -FF for a fiver they won't give me back, so how do you think you're getting any loyalty from me?"
O: "Thank you for your time, I'll call you back in a week shall I?"
A: "Make it two weeks, just to be sure the cheque clears first....."