cannot reconcile an account threatens to hand over

Clearly Lancet is a company who requires urgent competent collectors/accountants to manage their accounts. As I read through the thread of complaints, it is the same- harassment for outstanding monies, cannot reconcile accounts effectively despite showing proof of payment- pathetic. I sent them an excerpt from my medical statement for a payment made in November 2015 for an account incurred in hospital in Sept 2015. I am still up to today receiving emails, sms's and phone calls- all threatening to hand over to ITC. if they spent half the money on a proper accounting firm- they would be more efficient. I sent them an excerpt from a consolidated statement (for other provider confidentiality) which shows all the relevant info- date of treatment, payment date, payment value, from which benefit- everything is there. They now request the statement anyways- I may not be a genius, but what info will the statement have- that I have not shared? Nothing- except competitively sensitive info. Will make it a point when in hospital next to ask for Ampath or someone else!!