£500 per head for the wedding, not just the food Ah, sorry, I misunderstood as you were comparing the cost to a restaurant meal.
£500 I would think is high end. The venue must know what they are worth, and at what price they can sell a wedding. And has been explained upthread, you generally get a higher level of service and more included items, plus the extra marketing, staffing, and other associated costs with a wedding.
I know to the bride it must appear to be similar to a party, but it really isn't. Plus if the venue know they can charge £500 and will still sell weddings, then that's what they would do, they are a business after all.
I totally get why that isn't for you, a 'formula' wedding isn't for everyone. But I don't think it's fair to grumble that the venue won't give you what you want at a price you want to pay. They are offering a product (for want of a better word), and you choose whether to buy that product. Just find a way of doing it your way at a venue which will offer the product you want, which is what you did, and I don't blame you.
It's a bit like I choose not to shop in Waitrose, I shop in Aldi. Waitrose is more expensive, but offer a better service - free coffee, better choice of product, higher staffing levels etc. But I don't ask Waitrose to reduce the cost of my shopping because I didn't want the free coffee, or I returned my own trolley. I'd rather shop elsewhere if I want cheaper groceries.
Surely though, you knew the cost and what was included at the venue before you paid your deposit?