<em>(Good work, Fernando. Some of my comments in italics below as well. One thing to work on is sentence length and redundancy. A lot of what you write, while it may be technically correct and completely understandable, would never be spoken by a native. My corrections are mostly of that nature.)</em>
letter of complaint about a faulty microwave
Dear Mr Johnson
I am writing this letter to complain about an EFESA brand microwave (model number EQ4521) that I purchased on January 5th from your online store for £750. It is faulty.
I have been a loyal customer of yours <em>(this is implied)</em> for the last 4 years and have successfully made many purchases over the years. Unfortunately, however, this time I am dissatisfied with the service you have provided. The microwave has not performed as it should, it has failed to start on numerous occasions, uses a lot of electricity and never heat meals properly.
I understand that under the above legislation <em>(what legislation? Legislations are laws. You have refered to no law above.)</em>, it is your responsibility to resolve the matter.
For this reason I request that you repair the microwave at no cost to me or refund my money. I attach a copy of my receipt and the warranty for your information.
I look forward to your immediate response. If I do not hear from you within 10 days; I will take legal actions against your company. The costs of this action will be added to my claim.
If you wish to discuss by phone, I can be contacted am contactable by telephone at 54689715
Yours sincerely