harrasment of collection agents

I have a loan arrangement with Bayport which is a debit order however a lady that says she works for bayport collections a miss Debbie smith has been harassing me at work and just pitches up at my Job and even though i informed her that I was in meetings she proceeded to contact my work collages and manager to see where i was she forced me to sign documentation that i am not even sure what it was for it did not have any bayport headers and she brought her son with to my place of work she has also insisted that I send her a payslip to an e-mail which seems a bit ***** as it is not a bayport e-mail address and has told me that if I do not send it she will come to my house for it please can someone investigate as to what is going on