Once again, I offer my sincere apologies, I look forward to hearing from you soon.
Once again,  I apologize for our failure to serve you well. Thanks so much for letting us know. Your feedback is valuable to us.
So that I may investigate with our team where the problems lie here, and resolve them to your complete satisfaction, please could you contact me directly? My personal e-mail address is listed with this note.
In the meantime, I'd be most grateful of an opportunity to put this right for you. If you could contact me with your details via my e-mail address at the end of this note, I will get in touch to resolve the matter to your complete satisfaction.
Please standby and one of my teammates will get back to you with more details.
Your satisfaction is our number one concern and we promise to do our best to meet your expectations.
If you have any more questions, please dont hesitate to give us a shout.
Once more, really sorry for the inconvenience: we'll be in touch.
As a special apology, we're sending you a gift-token in the post and really hope that you'll try us again some time.
We all feel really embarrassed by what's happened and are sending you a gift token as an apology.

