As an Australian, I really appreciated the office of the Telecommunications Ombudsman, who would promptly and professionally deal with legitimate complaints. Telcos must have their own internal procedures for dealing with complaints, but where these are unsatisfactory, the Ombudsman would chase the telcos up, at their own expense. It meant a higher quality of customer service, more openness, and less deceptive practices.
Maybe Ofcom in the UK serves this purpose, but some other EU countries don't have the concept, and a customer must take (usually expensive and personally risky) legal action against a huge company for the €7 they overcharged you on dialed but non-connected roaming calls. (ok, in my case, they compensated me, but they probably overcharge millions of € per year with the same scam, and nobody polices that)