So Mark and Ash did not make a pact !
 

What liars they are ,they let Chris take all the blame.

What do you mean? They all made a pact and Chris was the only one to break it or so he thought so how did they let him take the blame?

Ash and Mark told the group that they decided to make another pact to take the money to make sure it got shared out ..That was the reason they gave for saying yes to the money

If Ash/Mark were going to share with everyone why did they not say NO ,just like Pav/Winston/Helen did.
Why did they have to be the custodians of the money

...exactly that Erin...

The pact was that the WINNER would share it with everyone. Not that some random housemate would. Ash, Mark and Chris said they'd take it because they knew that the pact was complete rubbish.

Ash and Mark took the money because they know they aren't going to win.
Chris took the money to give it to Ashleigh and Christopher because he knows there would never be an 8 way split EVER, especially after the Ashleigh/Chris/Helen row night before. The bad blood had resurfaced and they were not happy family anymore.
The others who refused the money ALL still believe they can win. Taking the money is the wrong thing to do if you think you can still win.
Everything else that happened was just a load of hot air.