UPDATE: Lolz, my mistake.
I obviously meant, top colour instead of pants colour. My mistake!!
On the plus side though. I had a few games of Local Mario Kart7 with my friends last night and received 10+ Mii encounters in a rom and BOOM!!
Everything sorted itself out. No more problems. I've got all my Mii's back +200!!! I can change the top colours and I can once again accept invitations so I get new Mii characters from MarioKart7 etc.......!!
What a relief. I was really considering sending my 3ds off soon as the problems were starting to seriously f**k me off.