Selenium webdriver select option - selenium

Question

I'm trying to select an option from a select drop-down using Selenium/java/MS Edge driver, but I'm finding I can't select the option even though I can see I have located it.
My code so far;
final static String URL = "http://usedcars.bmw.co.uk";
final static String edgeDriverBinary = "MicrosoftWebDriver.exe";
System.setProperty("webdriver.edge.driver", edgeDriverBinary);
WebDriver driver = new EdgeDriver();
driver.get(URL);
// Click the field to activate the drop down
By byQsRangeBtn = By.xpath("//div[#id='quick-search']/form/fieldset[#class='form']/div/div[#class='js-ctm-dropdownlist']/div[#class='js-ctm-display']/span");
WebElement qsRangeElement = driver.findElement(byQsRangeBtn);
qsRangeElement.click();
Sending this click does activate the drop-down and I can see it expands
Select qsRange = new Select(driver.findElement(By.id("qsRange")));
log("OPTIONS: " + qsRange.getOptions());
In the above I can dump .getOptions() and I see all the data from the select options.
When I call this I just get an exception with no stack trace or useful logging information. I've tried .selectByIndex() and .selectByVisibleText() with the same result - an exception and no information.
qsRange.selectByValue("3648835");
The part of the page is below. The id="qsRange" is set as not visible in the page (grey'd out in firebug). class="js-ctm-display" is the only div that is visible.
If I manually click the drop down to display it's values then <div class="js-ctm-dropdownlist"> becomes <div class="js-ctm-dropdownlist js-open">, but firebug still sees the select as not displayed.
<form class="quicksearch mp-search-count" method="post" action="/search-cars.aspx">
<fieldset class="form">
<div class="search-control series js-ctm js-ctm-mode-full" data-theme-type="dropdownlist">
<div class="js-ctm-dropdownlist">
<select id="qsRange" class="mp-control-data" name="Range">
<option value="-1">Series</option>
<option value="890">1 Series</option>
<option value="3648873">2 Series</option>
<option value="66">3 Series</option>
<option value="3648835">4 Series</option>
<option value="67">5 Series</option>
<option value="68">6 Series</option>
<option value="69">7 Series</option>
<option value="3648830">X</option>
<option value="3648831">Z</option>
<option value="3648832">M</option>
<option value="3648938">PHEV</option>
<option value="3648833">Hybrid</option>
<option value="3648834">BMW i</option>
<option value="3648879">Alpina</option>
</select>
<div class="js-ctm-display">
<span>Series</span>
<span class="js-ctm-ico"></span>
</div>
If I manually select a value from the drop-down then I see class="js-ctm-display" becomes as below and the page then makes an ajax call to obtain values for subsequent drop-downs.
<div class="js-ctm-display">
<span>4 Series</span>
<span class="js-ctm-ico"></span>
</div>
Because I can tell that the page is making multiple ajax calls as I move through the options I believe I need to simulate user interaction (clicks) rather than being able to just set values. However my attempts at clicking on an option in the list aren't working out at all.
I've also attempted to get a WebElement for one of the option values with the intention of sending it a click, but that throws an exception saying the WebElement is expected to be a Select rather than an Option.
Does anyone have a view on how to approach this kind of page? I'm rather new to Selenium so expect my approach isn't the best.