Thanks - got it sorted now.
4 line changes required in the code and now (hopefully) less questions from customers.
If anyone else is looking you can edit the "machform/includes/view-functions.php" file, search around line 8327 for these code lines (there are two of each):
<label class="description">Credit Card <span class="required">*</span></label>
<label for="cc_number">Credit Card Number</label>
Update where it says "Credit Card"