I have tried to make a question answer model using the open AI 0.28 and 1.34 but got a rate limit error (error code is 429).

I have tried multiple models in the below code. Even set a proper RPM but to no avail. Finally, I reset to this original code and posted the question. The code is below:

For version 2.8:

import time
import getpass
import openai

REQUESTS_PER_MINUTE = 3
SECONDS_PER_MINUTE = 60
REQUEST_INTERVAL = SECONDS_PER_MINUTE / REQUESTS_PER_MINUTE

api_key_input = getpass.getpass(prompt='Enter your OpenAI API key: ')
openai.api_key = api_key_input

if openai.api_key is not None:
    print(f"API key is set for {openai.__version__}")
else:
    print("API key is not set.")
def get_openai_response(messages):
    response = openai.Completion.create(
        engine='gpt-3.5-turbo',
        messages=messages,
        max_tokens=150
    )
    return response.choices[0].text.strip()
messages = [{"role": "assistant", "content": "Hi User! I happily provide assistance to queries."}]
while True:
    user_input = input("User: ")
        
    if user_input.strip() == "":
        print("Empty prompt entered. Exiting...")
        break
    messages.append({'role': 'user', 'content': user_input})
    try:
        reply = get_openai_response(messages)
        print(f"OpenAI: {reply}")
        messages.append({"role": "assistant", "content": reply})
    except Exception as e:
        print(f"An error occurred: {e}")
    time.sleep(REQUEST_INTERVAL)

For version 1.34:

import time
import getpass
from openai import OpenAI

REQUESTS_PER_MINUTE = 10
SECONDS_PER_MINUTE = 60
REQUEST_INTERVAL = SECONDS_PER_MINUTE / REQUESTS_PER_MINUTE

api_key_input = getpass.getpass(prompt='Enter your OpenAI API key: ')

client = OpenAI(api_key= api_key_input)
if client is not None:
    print(f"API key is set for {client}")
else:
    print("API key is not set.")

def get_openai_response(messages):
    response = client.completions.create(
        engine='gpt-3.5-turbo',  
        messages=messages,
        max_tokens=150
    )
    return response.choices[0].message.content

messages = [{"role": "assistant", "content": "Hi User! I happily provide assistance to queries."}]
while True:
    user_input = input("Enter your prompt: ")
    if user_input.strip() == "":
        print("Empty prompt entered. Exiting...")
        break
    messages.append({'role': 'user', 'content': user_input})
    try:
        reply = get_openai_response(messages)
        print(f"OpenAI: {reply}")
        messages.append({"role": "assistant", "content": reply})
    except Exception as e:
        print(f"An error occurred: {e}")
    time.sleep(REQUEST_INTERVAL)

Please tell me if I need to add credit to in their billing page or is it just a problem in the code due to which even the free tier engine is not working.