It seems that RM are regulated by Ofcom and yet Ofcom won't deal with complaints about them according to this 
https://www.ofcom.org.uk/postal-services/complaints-about-postal-service
It seems that RM are regulated by Ofcom and yet Ofcom won't deal with complaints about them according to this
https://www.ofcom.org.uk/postal-services/complaints-about-postal-service