Ah OK , good luck with your visa application , I take it your applying through London , they were quick with mine , about a week that's including resending photos .
I had a similar issue with uploading photos for my METV through the Thai embassy in London . They advised me to take a selfie in a bright room against a light coloured background , I ended up taking the selfie in my bedroom against the white walls with the light on , the photo got accepted no problem. Just out of curiosity how many times had you entered and what duration before they advised you to get a proper visa ?