The FSRH published a document in Mar 20 on what we should be advising women if they have not used their combined hormonal contraception correctly. There doesn't seem to be anything new in this guideline, but it is a really nice summary, with very easy to follow flow charts.
There is also very useful clarification on how to work out where a woman is after her hormone free interval (HFI):
"If a woman took her last pill before a HFI at 9am on Monday, so long as she restarts before 9am on Wednesday of the following week (just less than 9 days later) she does not need to take additional action. If she starts at or after 9am on the Wednesday of the following week (9 days or more later) additional action is required. For pills, the HFI is considered to start 24 hours after the last pill is taken."
I am also linking into the guideline on the use of emergency contraception (published in 2017) as you may need it to counsel these patients.