A few different issues in there - and for starters, buffering & pixellation tend to be two different faults.
Pixellation tends to only occur on live TV and/or recordings and be a symptom of signal problems (for live TV) or HDD-problems (if only on recorded)
Buffering generally only occurs on streaming and/or OnDemand content, and indicates a poor internet connection.
You mention having error codes, but not what they are? Or what you're doing when they happen? If you can be a bit more methodical about this problem - explain with some more details, and if you're willing to provide further info on this forum... you might well get some better help than the telephone-CS people can provide.
If there turns out to be a VM service fault, the forum staff can potentially pick them up without you needing to call. Upto you.