OK guys this is how I see it
Seema, you have evidence that a ip address was used to access your accounts and xentech's from what I can see in the forum The traffic was sent to a cc domain afaik these domains normally are used for drive by's and viral infections.
Xen - you have mentioned that you did not do it and posted a mail with some supporting evidence about the domain.
Somebody did do a check with Company's House to see if the Zentech name was registered and to see if it was registered to Xentech - no such luck. Unless Xentech did a viral search or malware search using tools online everything is hearsay regardless of what proof has been posted.
As for a legal perspective - currently the law stands in the UK that if you use somebody else's account details without authorisation to access their details or for any other purpose then you could be prosecuted, this even stands for using your neighbour's wireless to access the internet. You need to provide this to the police and this can be an online submission as there is an online fraud service that covers these crimes but as with all cases they are swamped and this type of investigation will be difficult to trace the originator of the compromise and traffic direction.
If xentech did provide a service to seema he must have to others on the forum, have they suffered the same fate? If not then it looks like a coincidence and makes it difficult to pin on him. Invariably doing it to one person means through behavioral patterns they will do it to other people. This is learned behaviour and if it brought any gain or pleasure then it will be repeated. If it was a revenge or malicious thing then he would not have stopped at just he PPV campaign but would have gone out to really do you over. It could have been a lot worse.
As this is a once of scenario then it is unlikely to be xentech but not improbable, what makes it unlikely is the time lapse between your pissed of I want justice post and his defense.
So overall where does this leave Seema and xentech? Seema out of pocket and pissed off with a certain amount of evidence of a single IP being used. Was this IP logged to the ISP xentech was registered to - don't know but he could ask his ISP to provide the range that they dish out or check for a reverse lookup.
Xentech is confused and tried to provide explanation - as said do a av check and spybot scan - this is meaningless as the scan will be out of date for supporting his innocence. There is a lack of proof as to innocence but also a lack of evidence outright of proven guilt. If xentech's pc was compromised then he would have had other issues with a load of identity fraud and bank details stolen - he can check that online to see if anything was illegally used.
If he has a server then that has been compromised to do malware infection. This can all depend how valuable they see him to be and what they can get down the line.
Suggestion to both of you - get your online identities checked. Verify your credit ratings. Check your bank details, change your passwords and find out if other problems have been caused without your knowledge.