(Solved) Trck Upgrade in LANDR

I Can't seem to find how to do this. I'm in the LANDR app, I've mastered a track in Low Res Mp3. Now, just to get a comparison I want master the track in HD Wav format. I understand I have to pay a one time fee for this.
 
On the LANDR website it states I have two free low res Mp3 masters per month, with the option of mastering a track in HD Wav format for $19.99. I just can't seem to find the right menu, or button to push.
 
Anyone know how to do this? It's probably really simple, and I'll kick myself once I find out how. Just having a blind day.

Thanks John, but for the moment, until I decide on how much I want to use LANDR, I'm going to stay on the free plan and just pay a bit extra for the tracks I need to master in a higher resolution.
It does state on the pricing page that you can have an 'HD Wav' master for $19.99 while on the free plan. I just can't figure out how to make this happen. I've emailed LANDR but haven't had a reply as yet.
Thought someone here may have tried this too. It's ok, I'm sure LANDR will get back to me, they have been great with their support so far.

Thanks Noel. I just received an email from support saying this exact same thing.
This is an extract from that email,
 
"Hey Wayne,
Angela here, thanks for getting in touch.
Glad you're trying out the app!
Unfortunately, there is no way to purchase individual masters within the app, so it really works most seamlessly if you're subscribed to one of our plans.
If you'd like to purchase tracks individually, you'll need to stick to our website.
Once you upload a song to LANDR.com, go through the mastering process and get to the part where you choose your format, you can select which one you prefer and then purchase that master on it's own.
Hope this helps!
Best,
Angela
LANDR Rescue Squad"
 
So, I'll give it a go from there. Thanks again for the help at this end.