My thanks and appreciation for all your help and personal support, particularly at a time when it was most needed... you were of enormous help.
I would never have guessed that making a will could have been such good fun.
You are worth your weight in gold.
Many thanks for all of your help (I couldn't have done it without you!!!). I have recommended you to my partner.
I would like to thank you for the service you provided and the valued support. Thank you again for a very efficient and effective service.
I would like to thank you for all the assistance you have given me and your kindness shown.