I believe you should accept that you are doing sales and practice for that. What you are perceiving as lack of regard for your good engineering skills might be only your own lack of regard for acquiring sales skills.

And if you are selling at anexo English speaking market, I also agree a lot with teovall's comment that you must improve your writing skills. I am not a native english speaker and Grammarly helps me a lot. I highly recommend this software for improving your writing in english.