adddd.phtml

<style type="text/css">
	.add-to-cart .input-text.qty {
		display: block !important;
		margin-bottom: 10px !important;
	}
</style>
<?php $_product = $this->getProduct(); ?>
<?php $buttonTitle = $this->__('Add to Cart'); ?>
<?php if($_product->isSaleable()): ?>
    <div class="add-to-cart">
        <?php if(!$_product->isGrouped()): ?>
        <label for="qty"><?php echo $this->__('Qty:') ?></label>
			<div class="qty-ctl">
				<button title="Decrease Qty" onclick="changeQty(0); return false;" class="decrease"><?php echo $this->__('decrease') ?></button>
			</div>
			<input type="text" name="qty" id="qty" maxlength="5" value="<?php echo $this->getProductDefaultQty() * 1 ?>" title="<?php echo $this->__('Qty') ?>" class="input-text qty" />
			<div class="qty-ctl">
				<button title="Increase Qty" onclick="changeQty(1); return false;" class="increase"><?php echo $this->__('increase') ?></button>
			</div>

        <?php endif; ?>
        <?php
        	$assignPro=Mage::getModel('mpassignproduct/mpassignproduct')->getAssignProDetails($_product->getId());
        ?>
        <?php if($assignPro['assignCount']): ?>
        	<?php if($assignPro['sellerqty'] > 0): ?>

        		<button type="button" title="<?php echo $buttonTitle ?>" id="product-addtocart-button" class="button btn-cart" onclick="productAddToCartForm.submit(this)"><span><span><?php echo $buttonTitle ?></span></span></button>

        	<?php endif; ?>

        <?php else: ?>
        	<button type="button" title="<?php echo $buttonTitle ?>" id="product-addtocart-button" class="button btn-cart" onclick="productAddToCartForm.submit(this)"><span><span><i class="fa fa-cart-arrow-down"></i><?php echo $buttonTitle ?></span></span></button>
            <div style="clear:both;"></div>


        <?php endif; ?>
        <?php echo $this->getChildHtml('', true, true) ?>
        <script type="text/javascript">
		function changeQty(increase) {
			var qty = parseInt($('qty').value);
			if ( !isNaN(qty) ) {
				qty = increase ? qty+1 : (qty>1 ? qty-1 : 1);
				$('qty').value = qty;
			}
		}
		</script>
    </div>
<?php endif; ?>