Abs fault w210
 

Hi i have a e class w210 e320 that has an abs fault i think. Everytime you brake you get a thumping noise from the rear louder the faster you go. it has been on an Ethos computer that showed WSS front and rear Left. I replaced with 2 second hand ones that havnt fixed the problem. Im thinking if i buy new will this fix or is something else wrong. Any help would be gratefully received.