1996 Mercedes C220

Look guys, Im and idiot. My dumb *** put powersteering fluid where the brake fluid is supposed to go. It took about a month for the fluid to take its course and mess up theREAR braking system. It locks it up as if i pushed down on the power brake. After i leave it still for about an 1 to 2 hours it releases the tension and im able to drive it for a short while. I had a Certified Mercedes Mechanic flush the brake fluid out and we tried driving it again, same outcome. He suggested to change therear calipers and if thats not the problem its the ABS module in the engine that has to be replaced and thats alot of money.

So where im getting is, is it worth the try in changing the calipers or not. It will cost me 290 a piece plus labor just to see if it works and if it doesnt then i out that money and have to decide on getting that expensive ABS module. remember its a 96 mercedes C220 is it worth it!!!