Вот это проверь по всей строгости IELTS
Dear Sir or Madam,
I am writing formally to express my dissatisfaction with the service 
in
 the Change preposition
at
hotel
. I would like you to know that I am a frequent guest Use synonyms
in
 the Change preposition
at
hotel
.
As a regular Use synonyms
customer
 I normally book a room two times in a month. Add a comma
customer,
Usually
 your Add a comma
Usually,
hotel
 provides excellent customer service Use synonyms
and
 breakfasts are splendid. Punctuation problem
, and
However
, when I stayed there one week Linking Words
ago
 I could not find a WiFi connection. Punctuation problem
ago,
Unfortunately
 my planned meeting was about to start, so I had to Add a comma
Unfortunately,
rebook
 it. The customer service support managed to return the connection only after four hours. Verb problem
reschedule
Linking Words
Consequently
 I have lost around five hours of my working day.
It would be great if you could provide an internal investigation and improve the quality of the internet in the Add a comma
Consequently,
hotel
. I would not like to stop booking your Use synonyms
hotel
 as it is really a good one. Use synonyms
Linking Words
Moreover
 I might suggest you Add a comma
Moreover,
to 
start using a spare WiFi connection for cases like Verb problem
apply
this
.
I am looking forward Linking Words
for
 your response. Thank you for your attention.
Yours faithfully,
Mikhail S.Change preposition
to