Revenge of the pump out loo

We have had Dampervan since October 2012 she has a pump out loo system called Tecma, its one with a machinator. All was well with the loo until last Monday when Tony was a work. I got home about 4pm and as soon as i got inside the boat i thought the dogs had had an accident.... the smell was that bad. In hind sight that would have been a whole lot easier to deal with. 

Now i don't have a very strong stomach and as soon as i saw what awaited me the retching started, what i discovered was that the loo had decided to push out all of its contents, 2 inches deep in the bathroom and down the hall carpet. 

I cannot begin to describe the smell, not having a mop bucket i grabbed the kitchen sink bowl and started to clean it up, cut a very long story short it took me 2 and half hours of hell. I had to un screw the skirting boards and rip up the carpet and lino. I boiled water to disinfect every surface in the boat and sat down and cried.

We had only pumped out 17 days ago, had no visitors so we thought we were ok, apparently not eh? The boat had always listed to the right, and Tony had spent a number of hours placing concrete blocks under the kick plates of the kitchen, under diner seating and even some in the engine bay. So Tony went to pump out, and the pipe was frozen so the marina defrosted it, ( Tony has been convinced that the marina pump out system hasn't worked properly since we got here) Once the pipe was defrosted it took 4 full 6 minute cycles to empty the boat. Tony is now even more convinced that it wasn't working before.

Once the boat was back in its mooring, Tony saw how far the boat was now listing to the left! He then took out 17 concrete blocks, now the boat slightly lists to the left, with the thinking being as the water tank fills up on the right side of the boat we will level out and it will help us to know when we need to pump out.

Tony has called the loo maker and he told him to check the outlet return valve, so thats why I'm sat in the kitchen writing this, so i cant smell it! While he checks. He has just checked it and all is good. So the only thing we can put it down to is that the tank was so full, that maybe some of it had frozen and then when thawed had become to much for it. 

If anyone has any other ideas please leave a comment, needless to say, we are now going to pump out every two weeks at the longest.

That was the scale of it...........