Visual mode messing up

Hello,
On my site I have a drop down selector with about 50 anchor tag options in it. It works perfectly until in edit mode it is switched from text to visual mode. once in visual editing mode each one of the options in the one selector creates its own selector and I end up with 50 individual selectors.
https://www.wwl.co.uk/wicks-and-wilson-resellers/
Here is what my code looks like but only showing a few of the options instead of all 50

<select class="form-control" onchange="if(this.selectedIndex!=0) self.location=this.options[this.selectedIndex].value">
<option value="" selected>(Select)
<option value="#aus">Australia</option>
<option value="#aust">Austria</option>
<option value="#bah">Bahrain</option>
<option value="#bel">Belgium</option>
<option value="#bra">Brazil</option>
</select>

Please help
Thank you