Formulate business letter correctly?

Have a business letter formulated as far as I'm not so sure if it sounds professional enough? Would be very grateful for your help and hints:

Dear Mrs. Mustermann,

We're a medium-sized IT remarketing company from Dortmund and specialize in reuse and recycling measures of customer returns and scrap products.

Since 2014, we have been buying used and defective electronics from various industries, including smartphones, tablets and notebooks for TOP conditions.

Your benefits at a glance:

DSGVO-compliant and secure data deletion
Free logistics with own staff
Top conditions, as well as fast payout

If I have aroused your interest in our company, then I would be pleased to welcome you as a new customer with us.

Of course I'm available for further questions from Monday to Friday between 09:00 and 18:00 o'clock.

In principle, I have stuck to your idea but incorporated suggestions or corrections. I also took into account that you should write either "we" or "me" all the time. The thing "free logistics…" I did not understand right; that could be the way other pesons do too.

I wish you success!

*****

We're a medium-sized IT remarketing company in Dortmund and specialize in reuse (s) and recycling measures of customer returns and scrap products.

For this purpose, since 2014, we have been buying used or defective electronics from a wide variety of manufacturers - including smartphones, tablets, notebooks.

Our offers at a glance:

DSGVO compliant and secure deletion of existing data!

We pick up the material from you on request!
Top conditions with fast payout!

Are you interested? We would be pleased to welcome you as a (new) customer (with us).

For (further) questions we're gladly at your disposal. From Monday to Friday (s) between 09:00 and 18:00 we're there for you.

Thank you so much.

Glad I could help! Please do not be angry, but we should leave that with the "friend". At my age, that is not my world anymore.

May I ask you one last time to help me with the wording of the subject?

I formulated the e-mail subject as follows:

Business Inquiry I
Purchase of unused & written off consumer electronics.

Do you mean it alright?

The text contains measures for the reuse or recycling of "used or defective electronics" as a corporate purpose. There should be no new terms in the subject, such as "unused & amortized consumer electronics".
I'm not clear what is meant by "written off" here. Is it about the tax term? Why this should be of importance to the buyer, I can't recognize.
The Et character does not fit in the context.

In my opinion, it suffices for the subject line "buying used or broken consumer electronics" or "we buy used or broken consumer electronics" or something lurid "we buy what you want to get rid of."

And then: If only consumer electronics is bought, that should be specified in the text so.

Many thanks for your helpful support!