The reply above covers all that I would say, except to add...
"If I ring the call centre they will just send another technician" which is exactly the correct (and required) course of action here. Either that, or wait for the forum staff to do the same.
But either way - it's a tech visit you need. You're not paying for them, but you are paying for a working service. If multiple boxes have given the same problem, then there's a distinct possibility the problem is somewhere else - maybe in your cabling somewhere.
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