On the back page............
THANK YOU FOR YOUR CUSTOM
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A VOUCHER FOR YOU
£5 off your next carpet clean
valid for 6 months : max 1 voucher per purchase
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A VOUCHER FOR YOUR FRIEND
£5 off carpet cleaning
valid for 2 months : max 1 voucher per purchase
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A VOUCHER FOR YOUR FRIEND
£5 off carpet cleaning
valid for 2 months : max 1 voucher per purchase
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On the other side of the page, your name and phone number, printed to line up with each voucher.
That way, every one gets a £5 off voucher, your customer and their friends.
Alternatively, why not get some £5 vouchers printed like business cards, and leave a few with each customer?