MTS.Krasnodar: even on prepayment you can get a bill for thousands of rubles. Do not believe? The court will assure you!

Surprised by the case of a relative: it would seem nonsense - prepaid rate, suddenly the phone is blocked in the morning, in the cabin they charge for more than a thousand rubles. (commercial services - followed by sex-on-call or something like that). Next - the theater of the absurd - MTS. Krasnodar sues and wins it. On the question of the prepayment limit, it is said that a technical failure occurred and therefore the connection was not interrupted after the subscriber finances. The court makes a decision - the subscriber is guilty, is obliged to pay all costs (3-4 tr).
How to be? The lawsuit is on appeal, there is a statement in the prosecutor's office ... but it seems they do not break through. Any ideas? Error or divorce? Why does the court go on about the technical errors of the corporation or is it a systemic failure against the “little” person?
PS Just do not la-la, the subscriber is an elderly person, pensioner, grandfather ...