Quick question: why isn't the latest version of the app available for my phone? Is there any way I could use a previous version?
The thing is, I got my phone just a few days ago and at the beginning the app worked perfectly fine, then out of the sudden its response became "Invalid application. Delete?" I took the phone to a Nokia Care center where they did a resoft or something like that but the app is still not working, I assume it is because it's no longer available for Nokia 302, is that why?
Welcome to the Nokia forum and thank you for making us aware of this.
If the application used to work, a software update should fix this. You can update the phone with Nokia Suite.
To make sure you won't lose the data on your phone, make a back up first. Click on Tools > Back up to do this. Once you've made the back up, click on the green arrow in Nokia Suite where you will see the available updates for your phone. If there's no update available, you will be able to reinstall the current software.
When the phone has rebooted, the application will work again.
Do let me know how you get on.