Re cross-selling emails: I just logged in to my netsol account (which was not locked, as I did not actually use this promo even for a few domains as I wanted, thanks goodness, they did not like my virtual prepaid cc which I tried to use for this promo) - and found that the reason I do not receive cross-selling offers is that I unsubscribed from any and all netsol emails - except obligatory technical ones - long time ago.
So they do have UNSUBSCRIBE option and anybody who is considering their emails as spam should probably use it, it is in account-profile settings
Unsubscribing, however, will likely prevent the system from sending any individual FREE TRANSFER offer should they elect to start another similar promo someday
I think there is no way to send domains back to original registrar simply because Netsol may wish to do so. Common ICANN-approved transfer form, which should have been sent out for any transfer (free or not) says:
"Once a transfer takes place, you will not be able to transfer to another registrar for 60 days, apart from a transfer back to the original registrar, in cases where both registrars so agree or where a decision in the dispute resolution process so directs."
Dispute resolution is either UDRP or another (2nd) ICANN policy which covers registrar-registrar transfer disputes. Neither applies in this case.
So it is likely that all affected accounts should have no issues restoring access and managing domains that were successfully transferred-in, maybe on or about Oct. 2nd.
Of course there is nothing that prevents Netsol from politely asking "please pay us some $$$ as we messed up the things". Maybe it is the only thing they can really do. I may well be mistaken, in fact any lawyer should be able to give better recommendations to all parties after carefully reading their TOS