To add, all the symptoms you've explained are consistent with hard drive issues - this would affect all recorded content. If incoming signal was the fault, then this would affect live TV, which you didn't mention in your original post.
To prove an HDD issue, use your main box (not any minis, these just stream from your master box) to view live TV. Now pause it for a short time, and watch delayed - this is effectively a recording and uses the hard drive in the same way.
HDD faults should be reported in the same way as any other service fault - call in for an immediate response, or wait on there for staff reply in a say or so. Then the tech will very likely replace the affected box.