CALLING ME ON MY OFFICE NR

After numerous attempts and requests to Identity to be contacted on my cell nr they keep on phoning me on my work nr. We are not allowed to receive calls during office hours. This is an open office and everybody can hear the conversations. This morning once again they phone the office nr leaving a message I must contact Identity regarding my account. I know I'm in arrears and I did explain I will make pmt. I had a terrible financial problem due to my husband who went into hospital for an operation and came out disabled after the operation went wrong. How many times must I still ask Identity to be contacted on my cell nr. I'm checking my calls. I do receive calls from a 087 nr but if you phone back the nr doesnt exist.