Invalid Biller selected response

Hello, I was trying to purchase Airtel Data Bundle using the API but it given me this response (Invalid Biller selected).
Below is my postdata and params. What am I doing wrong

$postdata = [
‘country’ => ‘NG’,
‘customer’ => $a_number,
‘amount’ => $a_amount,
‘recurrence’ => ‘ONCE’,
‘type’ => ‘BIL110’,
‘name’ => ‘BIL110’,
‘biller_code’ => ‘BIL110’,
‘is_airtime’ => false,
‘country’ => ‘NG’,
‘biller_name’ => ‘BIL110’,
‘reference’ => uniqid(time())
];