this is the response i got from support
but i was clueless how to apply their feedback !...
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Whilst the Product Group Headline and Tagline fields do not currently support HTML input, we welcome feature requests online at http://requests.whmcs.com
Feel free to suggest this as a new idea for comment and voting upon by other WHMCS users.
The more votes an idea receives, the more likely it is to be considered by our development team for potential inclusion in a future feature update.
In the meantime you may be able to achieve the desired result by customising the template which controls the appearance of the page directly (/templates/orderforms/$templatename/products.tpl).
For more information on customising the appearance of WHMCS, please see: https://developers.whmcs.com/themes/
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thanks,