oil pressure high megane scenic 1.9 dci 2003?

oil ceals have been pushed out on oil filter, i've replaced this part but it still does the same, turbo was makinga wining noise for about 6 months, took to garage and all they did was change a valve and the cam belt, wining persited. there was a rattling noise coming from around the pully area of the engine and the cam belt tensioner was jumping around like a mother*******! could this problem with the oil pressure have something to do with the oil pressure release valve and if so were is this valve located.
thanks all who may be able to help.

kind regards Nick