I got a 4 wheel alignment the other day, and the fella apart from having not much of a clue stuffed up and gave me the wrong toe that I asked for. Took it back in and let them know, they said "OK sure we'll have a look". Got the car back, they were all smiles, now my steering wheel is at an angle when the car is going straight. Are they messing with me? What causes this?

I reckon they played a game. If it tracks true and feels good, take off steering wheel and put it on straight. Unless your alignment was way wrong

The alignment shop should make sure the wheel is straight. Let them know it's not quite right yet. They will eventually see they must do it right or you'll keep bringing it back.

If you move the wheel and the steering gearbox is not centered it still won't be right. Let them fix it.

I have my doubts they did a 4 wheel allignment. Cant imagine any work was carried out on the rear end.

They don't align the rears but they can check thrust alignment. Did it on mine recently. Makes sure diff installed straight at least.

Any good wheel alignment will give you a total rear toe, but they will not touch the rear cos they arnt adjustable so if u paid for a 4wheel alignment u got ripped, and what total toe did u ask for and y? also did u have or do u have adjustable anything apart from tierods?? ie camber/castor ect!
Try do a swing test turn the wheel one way and count the turns from where the wheels apper to be straight and then do the same the other way! If they are the same then the steer rack is centered and the wheel isn't so u can remove the wheel and center it yourself(but leave the wheel nut on a turn so u don't ko yourself!) if from center to either side is differant take it back or take it to a specialist! If yor in south east Melbourne I can help out!
Need more info just ask ta nick

Should have mentioned its a non-datto with IRS. Toe only adjustable on the front and toe and camber on the rear. I wanted toe out on the rear and negative camber and they didn't do it, which I should have suspected since they have probably only ever done standard alignments. The steering wheel was straight as before I took it it. I'm just going to bust out a string and do toe myself from now on, any problems doing it this way?

From what I can figure out, if I straighten up the steering wheel then adjust the tie rods then it should all work out? Then fine tune it with a string parallel to the hubs

Nah, you must first find center as superfatto described:
Quote:

After that is confirmed, then you can adjust toe.

Ideally you'd want to check tied rod length and compare side to side. If they are uneven (and assuming your car's suspension design was done well enough) you'll be introducing (or likely as not, exacerbating) bump steer.

I'd go for even tie-rod length/thread engagement, and if need be pull the steering wheel and re-position if necessary.
On Aussie valiants, the steering wheel isn't re-clockable as is, and a lot of people run uneven tie rods for a 'centred' steering wheel and it worsens the bump steer (they are ok in stock form as long as you don't lower them too much) The smart guys pull the steering wheel hub and carefully file down the 1 thick spline so that the wheel can be re-clocked at any position).

This probably won't be necessary on your car, but I'm just adding it to give some sort of 'feel' for the importance of tie-rod length.