1 st, you payed them to fix it,they have not fixed it, your entitled to your money back.( If they wont give it back, and you payed by bank card, the bank will get it for you, speak to them they will send you a from, it will take some time tho)
2 But talk to the garage first and tell them its not fixed, show them the relay banging thing, to prove your case, and ask for the old parts back, because they are yours, you want proof they actually did change the part, and because abs ecu can be repaired, which they did not tell you about.
3 ask them what the diagnostic results where from tech 2, they should have plugged it in to diagnose, but i bet they bloody didnt, sounds like they where just throwing your money at it, and guessing to me. If they did not run diagnostic, you need to get that done in my opinion.
4 no idea whats actually wrong with it but does sound like its a in the relay box from what you said. For now tho, try the paper clip test and post the results.
5 there are always far more experienced people on here than any dealer i have ever been to so, you prob now now, ask on here first, before the thiefs rob you again,... Oh and keep on top of your service schedule it will pay off 10 times over esp. if you do it yourself and then your cam belt wont break!
Ps sorry if that lot sounds a bit shouty but dealers really get my back up. Good luck.