Coolant leak W203 c220cdi

[Dvdmike]

Hi all,

I have been losing coolant with no over heating issues for a while and when I had a service today they said: The top hose to the thermostat is leaking.
I know bits and bobs but not a lot the guys who did the service don't do things like that, but said it's an easy fix and cheap?

Can anyone please advise on complexity or on cost and parts needed?
I looked and there are a few different hoses and I can't see if a novice can do it?

Thanks in advance for any help

 

[Dvdmike]

Oh and he also said you only need distilled water whilst it's leaking to save money?

 

[Dvdmike]

Can anyone help