Write in the first person - use 'I' and 'we' not 'Progress Housing Group'. Call the reader 'you', as you would if you were sat across a table from them or speaking to them on the phone.
Use the active voice. This automatically makes your communication better and more professional, instead of stuffy and bureaucratic.
We tend to use the active voice naturally when speaking without even thinking about it. It’s when the subject of a sentence does an action to an object. We sometimes change to the passive voice when writing. Here are some examples showing the difference between the two and how the passive voice can be turned into the active voice:
This matter will be considered by us soon (passive)
We will consider this matter soon (active)
The riot was stopped by the police (passive)
The police stopped the riot (active)
Instructions will be given to you by the operative (passive)
The operative will give you instructions (active)
The boiler was fixed by the operative (passive)
The operative fixed the boiler (active)
Repairs are reported by thousands of tenants every year (passive)
Thousands of tenants report a repair every year (active)
You can see how the active voice is more straightforward and easier to understand.
Sometimes a passive voice is better to use. For example, to make something less hostile - 'the rent has not been paid' (passive) is softer than 'you have not paid your rent' (active). It may also be kinder to say 'I’m sorry to hear of your partner’s death' than 'I’m sorry your partner died'. But you should aim to use the active voice most of the time.