Hi,
In my expereience of washing up liquid, the resoiling is due to the detergent residue. The detergents are pretty stable and you will not be able to break them down. The only thing you can do is to flush out the residue with bucket loads of water.
I would use a stair tool and lift the effected area up. This is hard to decribe, but dont push the tool into the carpet, try and raise the carpet up using the suction from the tool. Then i would just keep rinsing it, over and over, until it stops foaming.
The last time this happened, i probably used 10-15 litres of water on a square foot to fully remove it. She had spilled quite a lot of fairy on the carpet, so your mark might not be as bad. I was thinking of lifting the carpet off the gripper, but didnt need to in the end as i dont think it had penetrated through the action back.
Remember to use a lot of anit-foam in the waste tank and coninually check it and remove the foam.
Finish it off by doing a few minutes of dry strokes as the area will be pretty saturated. Warn the customer that the area is likely to take slightly longer to dry.
Hope this helps
Graeme
Access Cleaning Solutions