Just spet the last 2 hours bleeding the coolant system. Followed all the usual guides and all went well. Funny thing is that the temp gauge never went over half way even though the car was running for nearly an hour and a half while being stationary. Rad fans came on a few times but ony on low speed.

Whereas I bled the system yesterday and drove the car 3 times for 30 min at a time and the temp Temp only went up when I pulled into my driveway after the third run. Let it cool down and put another 500 ml of water in the system. Which isn't out of the ordinary if you believe all the bleeding guides.
Consider me stumped.

just tell us what happened without the specific name of said mechanic if you don't wish to be flammin.

The name of the mechanic is very important. Otherwise you wont understand just how f**k*d up this whole saga has been. Say I took the car to Joe Habibs Mechanical repairs and he stuffed up? You would say "what do you expect, its old mate Joe working on the car he doesnt know toyotas or MR2s". However Say I took the car to a Toyota "Guru" as they are known and he stuffed up, well that puts a whole different spin on the whole matter. Ill tell anyone who asks via pm.

You're using red coolant right?

Nope, the "Guru" used green coolant

MR2QIK. What do you make of waht i described in these two posts?
 
"Just spent the last 2 hours bleeding the coolant system. Followed all the usual guides and all went well. Funny thing is that the temp gauge never went over half way even though the car was running for nearly an hour and a half while being stationary. Rad fans came on a few times but ony on low speed."
 
"Whereas I bled the system yesterday and drove the car 3 times for 30 min at a time and the temp Temp only went up when I pulled into my driveway after the third run. Let it cool down and put another 500 ml of water in the system. Which isn't out of the ordinary if you believe all the bleeding guides"
 

just say "a well known toyota mr2 specialist mechanic" who shall remain nameless did(or didn't do) such and such.
 
to all those not in your state it will never matter who the mechanic is.
 
anyhow, it sounds like your problem is now fixed yes? if so i'm happy for you that it's sorted at least.

The Car still overheated yesterday after bleeding it. Haven't driven it today after bleeding it again, but the fact that it didn't overheat when running with the car on stands for an hour and a half has me confused.

How are you driving it? is it seeing boost?