Originally Posted by Ricky Bobby

This is the key statement which tells me your air pump, whether replaced with a new one or not, still has issues. When I replaced mine a year and a half ago, I bought a used pump off a member on here which came off a 30k mile X, so it was fairly new. however, I would not recommend a highly used air pump because the seal does have a tendency to degrade and that is why it can't fill the bags quick enough.

Here is a link to the air pump repair kit that you need to install on your air pump to hold the pressure better, it comes from jolly ol' England:

Mercedes E Class s Class Wabco Air Suspension Compressor Pump Seal Repair Kit | eBay

Install it on your pump, reinstall in the car, and reset the faults. Your air suspension should be fine after that (with any issues relating to the above)