Sing4me88 is spot on IMHO - it is not about the pitching service you use it is ALL about whether your songs have a commercial value for a particular pitch/opportunity (and I conciously didn't say whether your songs are "good enough")
The days of submitting a demo tape/CD of an album of songs you have already written/recorded to a publisher, label, artist to decide how best to use them seem to be gone
The chances of one of these existing songs being a perfect fit for an artist or pitch are quite slim, especially if you have written the songs "for yourself"
You will be up against the "best in the business" when pitching songs - and these guys will have access to studios, session musicians, experienced co-writers and most importantly would have done their homework dissecting the billboard top 40 to ensure what they are writing is what the industry is looking for - or they will receive a pitch request a write a song specifically for this opportunity
It is much more common for a publisher to "reach out" asking for a specific type of song - so the good writers either already have a catalogue of songs that fit what the industry is looking for or they will write one to the brief
So, my advice for you would be:
1 - post your songs (1 every 2 weeks in accordance to the website rules) in the feedback forum and ask for specific feedback on the commercial viability of your song - indicating who (artist, genre etc.) you would intend pitching it to. This will get you FREE advice from some members that have experience in the industry and also general advice / feedback from other aspiring writers
2 - join GISC - the Guild of International Songwriters & Composers. I think it is around £80 for a year's membership and they offer a "song critiquing" service to determine the commercial viability of your songs. This is the cheapest way to get proper industry feedback on a batch of songs
3 - ONLY when you have a clear idea of who you are writing for and your songs have a chance of standing up against the competition would I suggest considering a pitching service. The good ones are quite expensive and the cheap ones rarely lead to anything (and some question whether the leads are actually legit!)