I don't think that's the right question.
It shouldn't be "where is the money coming from?"
The question should have been:
"What was the money that should leady have been in their salaries being spent on?"
Public services are nor a piggy bank to raid, especially when MP salaries were rising in thr same period.
Doctors and public services cost a certain amount. Like anything in life, if you can't afford them, reevaluate your overall budget and make cutbacks. I can't choose to pay Tesco staff less because I don't like thir food prices; I can choose to shop elsewhere or buy different products.