Rescheduling: How long is too long to hear from a lender?

Hi,
I approached and had a meeting with my mortgage lender five weeks ago, requesting a period of interest only. She was helpful and symphatetic. I had all the information she needed, and she even suggested I was under-estimating my straits (medium-term temporary).
Haven't heard a word back since. Have tried to contact by phone three times last week and have sent one email directly to her.
How long should one wait before getting worried in these situations? I noticed nothing in the Code of Conduct on Mortgage Arrears about the length of time in which a lender should respond to a

Five weeks is far too long. You need to drop into your lenders branch and follow the issue up asap.

Grrrr! Contacted branch to find that manager had gone on leave. Have phoned twice and sent two emails to assistant manager since. Going on seven weeks now.

Took three months in my case due to backlog.

Thanks Ireland.1 . But I'd appreciate if they had the courtesy to let me know if there was a backlog ... I've heard absolutely nothing ...