To be fully compliant PS 1.6 you should use:

<div class="col-xs-12 col-md-6">
        <p class="payment_module">
            <a class="realexredirect" href="{$link->getModuleLink('realexredirect', 'payment',array(),'true')|escape:'htmlall':'UTF-8'}" title="{l s='Pay by Credit or Debit Card' mod='realexredirect'}">
            	{l s='Pay by CB card with Realex Payments' mod='realexredirect'}
            </a>
        </p>
    </div>

Warning: This piece of code could not work on PS 1.5, you should try and select the appropriate template. One for PS1.5, another one for PS 1.6.