From their website.
How can I get my OMRON blood pressure monitor re-calibrated?
With all OMRON blood pressure monitors, the recommended time between calibration depends on the use of the product. If the monitor is being used in a home or personal environment, we recommend they are re-calibrated every 2 years. If the monitor is being used in a clinical environment such as a doctors surgery, we recommend that this is done annually to ensure the accuracy of the results.
OMRON blood pressure monitors all come with a 3 year warranty from date of delivery. If you still have a copy of your receipt or invoice, we can service your monitor free of charge for 3 years from the date of delivery.
If you wish to proceed with this, please follow the below instructions to ensure a quick turnaround.
You will need to include:
A brief note stating that your machine requires servicing & explaining the issues you are having with obtaining readings, if any.Your return address details - Items are sent out via our nominated courier so the return address needs to be where someone will be available to sign for it.A daytime contact telephone number.A copy of your purchase receipt or invoice (showing purchase within the last 3 years) so that we can carry the work out free of charge.
Alternatively, feel free to contact us with the serial number on the back of the monitor so that we can check when the monitor was manufactured as we can start the 3 year warranty from the manufacturing date if you no longer have a receipt. If you have had your monitor for more than 3 years, we can of course still service it outside of warranty - There is a standard charge of £30 for this which is payable by cheque made out to "OMRON Healthcare UK Ltd."
Mailing address:
Technical Customer Services
OMRON Healthcare UK Ltd
Opal Drive
Fox Milne
Milton Keynes
Bucks
MK15 0DG
We aim to have your monitor returned to you within 7 working days.