Quoting phrases with spelling errors

Hello

I am writing a report at work and I need to put in a fair number of quotes from comments our customers have made for our customer surveys, as examples of trends or points I'm making.

Problem is, many of these have a lot of incorrectly spelt words and a lot of "TXT Speak" abbreviations.

For professionalism and read-ability I'd like to correct the spelling (and in some cases, the grammar) on them, but am I then mis-quoting in any way, as the quote will no longer be the same as the customer wrote it?

I can't put [sic] after every single one, it would render all the quotes even more unreadable!

The audience of the report is management and exec. level, so it needs to be professional, however it does not need to be completely formal and correct like an essay.

Any advice welcome.

Regards

Monica