Renault Megane strange noise from the rear

hi fletch
there are so many causes & as your description is rather vague,to say the least makes diagnosis even harder. however here's a list you need to check before spending your hard earned cash.
1. de-clutter your boot space, then road test.
2. check your sparewheel carrier is bolted up tight,road test.
3. check tightness of road wheel nuts/bolts, road test.
4. when exhaust is cold, tap tail pipe lightly but firmly with your hand,as there may be a broken mounting/insulator allowing exhaust system to foul on under body of car & by tapping tail pipe you will be able to hear if this is so.
5. see if any mudflaps are breaking away ( if fitted ).
if none of these sort problem, then re-submit problem, with MORE info & i'll try to see if i can help further, or seek local garage help.
let me know how you get on. regards dj dave.

check the rear shock absorber has not snapped or become loose or out of it's rubber bushes