Iberbanda is actually owned by Telefonica/Movistar.
When I had their system, it was fine, good value for money and I never had any issues with the service itself.
Indeed the only problem I had, was when it came to cancelling the service when moving house and was moving to a location where WiMAX wasn’t available. A year after cancelling, I received a solicitors letter, saying I owed Iberbanda about ?70 for cancelling the contract. Needless to say, they were wrong and I had the correspondence to prove it. Always keep copies of your bills and any correspondence you have with them, as I suspect their administration isn’t the best.
A minor snag in the end, but connection speeds and reliability of the service itself, I had no issues with.