Whats causing this now?

Take the car to his house/garage. Wait until dark, then set it on fire. Obviously he has been ripping you off for years. Watch his useless, pathetic, attempts at being a mechanic go up in smoke. Claim on your insurance, buy a new car and find a decent mechanic.

Walk away from that car! Your cylinder head was probably warped when it overheated, or it may have a serious, terminal crack in it. Equally, the cylinder block may be out of flat, and may need "decking" - this is ok if you have a big wallet, and a rare performance engine, but for a quotidian drudge such as an Ashtray, just move on and hope to be more lucky next time. The secret to both good comedy, and cam-belt changes is....... .... TIMING! The belt is something with a set lifetime - it needs changing every 40,000 miles to be safe - and the pulleys it revolves around, and the tensioners that keep it in place, must be checked and renewed if they need to be. Once a cam-belt fails in service, there is a good chance that the engine has sufferred a serious, uneconomic repair. Yes, you are showing signs of head-gasket failure again, and it was up to him to make sure that simply changing the gasket would be a viable repair. Talk to him, see what he says, but I would just go for another car.

Your head gasket still a problem. Maybe the gasket it self got changed but if the heads were not sent to be checked for flatness, then you still have the problem. It is going to be pricey, sorry.

damaged head/head gasket

sounds like he may not of found the cause of your problems and has only fixed part of the issue, the smoke is not good and the oil in the coolant is not good, dont drive your car it'll only get worse, smoke only on start up new head? did he forget to put valve stem seals on the valve guides? oil in the coolant is it a mouse texture or just residue film on the top, it may be left over from the repair ? you need to give him the chance to rectify these faults or at least explain whats wrong now ind if its related to whats been done previously, dont take your car to someone else dont use it just wait for him to get back,

It sounds like the cylinder head gasket has gone. Since he apparently already fixed it you shouldn't have to pay another penny to get it fixed properly. I've been in exactly the same situation with my MG. I'm so sick I'm just getting rid of it and getting a new car. I think it's time for us both to change mechanics, even though mine's pretty trustworthy too, they should do it right first time.

well considering the cambelt went! that opened a whole world of problems! im not a professional mechanic so i don't know the procedure for fixing that! the smoke coming out of your astra is the oil burning! you proabably have worn o-rings, oil in your coolant is not a good thing thats going to cause your engine more problems! your car is proabably going to die with a broken gasket or a worn catalyic converter! just get a new car! someone been driving the car too hard or not allowing it to warm up! your trouble is not going to end! and its not your mecanic's fault he can only fix it as it occurs but it will never be truly fixed unless you go head over heels with the expense!

Oil in the coolant or coolant in the oil is definitely the head gasket. If he fixed it in the first place there should be a guarantee on the work if he did it legit.

is it the 8 valve engine, if so wil be the h/gasket renound for this,