i overcame this problem (and im with fido too by the way) by using xavi's w510 monster pack. i'm now able to use mp3's as ringtones by simply going to "apply as" (its now shown in my menu. before it wasnt). thanks to his monsterpack. download it =P
Im not sure about it voiding the warranty but they dont tend to check the firmware when you return, exchange or do anything of the sort, so just play stupid :P thats what i did.. question tho, you dont have to unlock the phone in order to flash do you ?
English is usually included in all LPs, so also in all MPs. you can use any other 510 MP, and flash only the LP with FB3 for example, if that works for the W510, or changs it in the Phone, but you need probably to find the setting first. Its under initial setup, language. whatever that might be called there. Whart language do you have at the moment on the display?