Judging by the set of photos, that pipework is an abortion - as well as being a loop-the-loop, it seems that there's even a section of 15mm pipe near where you say it's blocked.
Whoever changed the rads should be capable of doing this work. Excluding draining and refilling it would take a professional less than an hour. The cost depends on the method of charging by the person that you engage.
Whoever changed the rads should be capable of doing this work. Excluding draining and refilling it would take a professional less than an hour. The cost depends on the method of charging by the person that you engage.
