Help with lowering k11 micra

Hi there folks I'm pretty new to this website I'm looking for some coilovers for a k11 or even back springs. I currently have it on gaz at the front with corsa b rear shockers by spaxand p.o. springs but it's banging on the back exhaust isn't touching axel and nothing is catching or touching anywhere searched high and low and everything seems ok but it's banging knocking and rattling from rwae so no idea what's going on.
I'm willing to but new suspension but not paying stupid prices at the minute there must be someone who can sell a complete set of coilovers for a reasonable price if
Hi there ill currently selling a set of FK Corsa B coilovers, never used still in the box brought for my micra but no longer need them.
Looking for £130 for them if you are interested.