iPhone security question I think I made a rather stupid mistake

My iPhone battery was getting old, so I went to a local repair shop to get it replaced. It's not an Apple Store, just a  couple of guys who fix PCs and do odd jobs like that.

They agreed, and said I could come back in an hour. When I came back, they said the phone was ready but asked me to provide my PIN. I don't know why this was necessary, but stupidly, I gave it to one of the guys. He turned on the phone, then unplugged it and gave it to me.

I now realise that in the time I had been gone they could have taken an entire image of my phone onto their PCs. They now have the PIN too, so is this  a massive security risk for me?

I have changed all the passwords to all the emails, facebook, and Apple ID. No idea what else could I do? I feel really stupid for giving up the password to them.

What could they do with the the data they (might) have? What is the possible damage? Any steps I could take to minimise any possible harm?
From your description, they had the PIN for only the time it took to unlock it, check it was working &amp; hand it to you - a matter of seconds. 

There's nothing else they can do with it unless they also still have your phone.

The PIN itself doesn't provide access to anything other than the phone, has nothing to do with your iCloud account, App Store, iTunes, email... or anything else.

In you post you mention both the PIN &amp; the password. These are two entirely different things. You ought to edit your question to clarify which you actually mean.