IELTS TASK1:Complain letter for wrong information on a product's AD

I hope you guys can help assess the letter I composed.an IELTS band score would be great
all comments and suggestions are welcome..thanks..

Task :
You have purchased an item after gone through an advertisement. But some of the information in the advertisement, was wrong about the purchased product. Write a letter to the manufacturer about it. In your letter,

- mention the product you purchased and about the advertisement
- what went wrong with the information and describe your problem
- what you want the manufacturer to do and ask for the solution

Dear Sir / Madam,

I am writing to express my dissatisfaction on one of your latest television product, particularly Smart TV EX500.I purchased a set 3 days ago from one of your authorized retail shop in Southlane street. I was disappointed when I found out the unavailability of the wireless feature.

As advertised in television commercials, I was expecting that this model is capable of connecting to the internet without any hassle. After unboxing and experimenting, I discovered that the unit requires a dongle for wireless functionality, which is essential if associating the unit to internet. Not only will the dongle cost me additional 300 dollars but it will also take a couple of weeks to be delivered. I hope you understand how upset I am to be in this situation.

Overall I have decided it is better-off to upgrade the unit to a higher model. I need your assistance to approve my request to trade the unit I have purchased with Smart TV SX500. I am prepared to pay for the price difference if necessary. I would also suggest that you review the advertisement for this product to avoid future unhappy customers.

I hope to hear from you soon.

Yours faithfully,
Chandler

Wow, well I thought it was very easy to read and it got all of your points out without sounding barbaric. I was not sure what IELTS was until I looked it up and was surprised that you are not a native English speaker. I would give it a high band (8.5-9). Sorry if I can really criticize it though. It sounded great to me.

Yes, this has some grammar errors that have been already highlighted by others and the fixes have been suggested by them. In addition to that, I wish to say that you need to take off the word "particularly" because as your prompt suggests need to talk about one specific product that you purchased. It's important that you always keep your writing aligned with your prompt.