Probably they can't, but they could give me courtesy bike for the time of repair free of charge, which they simply don't want to do...

This wasn't my fault - the part was just faulty. I didn't argue that since they offered, that they will fix it anyway. Would it change anything if they weren't doing that as the gesture of good will ?

So basically they can keep my bike for how long they want?

Hi! 2.5 months ago I bought preregistered Honda CBF125 motorcycle. After 2 weeks when I was changing the oil, while unscrewing the oil drain bolt, the part above it cracked. I went to my nearest Honda dealer and learnt that I wasn't supposed to change the oil myself(even though the official manual states different) and this won't be covered under the warranty. He offered to fix it for JUST £900. I wrote official complaint to Honda UK and "as the gesture of goodwill" they agreed to make the repair for free. It has now been 2 months since I left the bike at the dealer's workshop. Every week I was being told that the parts will arrive in the following week. Yesterday I've been told that they won't be able to get the parts till August. They will try to get them earlier from different source, but they don't know when. Is there a maximum time that they can keep my bike? I didn't buy a bike to have it repaired just before winter...